We plan to use pulsed NMR techniques to study the properties of water in normal and sickle red cells under a variety of environmental conditions. Preliminary experiments have shown that water motion is greatly impeded by the sickling process. Careful measurements of the spin-lattice and spin-spin relaxation times of the water protons, and particularly, measurements of the spin-lattice relaxation time in the rotating frame will allow us to characterize the type and extent of microtubule formation. Assay methods will be developed for use in monitoring the effects of chemotherapeutic agents on HbS polymerization. Suitable control experiments on normal cells, oxygenated and deoxygenated cells, and hemoglobin solutions are proposed.